In this article, we would like to take a closer look at mirror therapy. Compared to conventional therapy, thanks to VR it is possible to add a virtual mirror at the push of a button. In this article, we will show which exercises are performed as part of mirror therapy, what mirror therapy has to do with phantom pain, and what advantages CUREO offers.
Mirror therapy is a method of therapy for hemiplegic patients. In conventional therapy, a mirror is placed centrally in front of the body for this purpose, so that the patient sees the healthy limb and the mirror image of the healthy limb. The healthy limb is then subjected to touch stimuli or moved by the patient to transfer this stimulus to the impaired arm.
History of mirror therapy
The method was invented and applied by Vilayanur S. Ramachandran and his colleagues in 1996 [1] to stimulate sensations in phantom limbs by visual stimuli. Even this first study showed that it was possible to transfer sensations from the healthy arm to the mirrored phantom limb and thus to the impaired arm. Thus, some patients were able to release their cramped phantom hand, through the visual representation of the healthy hand in the mirror. In addition, one patient was able to move the fingers of his previously paralyzed phantom hand again after a total of three hours of training with the mirror spread over three weeks.
Mirror therapy for phantom limb pain
These great successes pointed the way to using the mirror in therapy for patients suffering from phantom limb pain and stroke-related paralysis. Results showed that the brain can dynamically and interactively adapt to new circumstances and re-learn skills even in adulthood. In addition, it was pointed out that this meant reconsidering the previously held view that the brain was hierarchical and modular. This was a first step in the direction of research into the neuroplasticity of the brain.
In further studies with imaging techniques, brain activity during mirror therapy was measured and it was found that mirroring movements lead to activation of the opposite hemisphere of the brain (contralateral hemisphere) in each case [2].
How does mirror therapy work?
Mirroring causes the brain regions responsible for perception and movement of certain body areas, such as the upper extremities, to be stimulated. This stimulates the brain's plasticity to form new connections so that a new body image can be formed [3]. Among other things, the function of the mirror neurons is also activated. These are neurons that show the same patterns of activity when viewing a movement as when performing the movement. Brain activity is lower during mirror therapy, i.e., viewing the movement, than during the actual movement. This is beneficial because it also means that pain stimuli are less activated and new movement patterns can be learned without severe pain [3].
Mirror therapy is a long-standing approach for various indications such as neglect and hemiparesis (Dascal et al. 2018) and has been used successfully for the following conditions, among others [3]:
CRPS (complex regional pain syndrome).
Phantom limb pain
Stroke
Parkinson's disease
Multiple sclerosis
The efficacy of this therapeutic approach has been demonstrated by numerous studies reporting significant improvements in upper extremity function and occupational performance (Bondoc et al. 2020; Thieme et al. 2018). Moving this established therapy approach to a virtual environment has been shown to result in similar improvements.
The integration of VR-based therapy represents a promising and accessible new tool in motor rehabilitation and pain management (Giroux et al. 2018).
Mirror therapy exercises with CUREO
CUREO offers a very good way to help hemiplegic people through virtual mirror therapy. The immersion in the virtual world through the avatar achieves an additional positive effect. Furthermore, the patient can move freely in the virtual world and look everywhere without being restricted by a real mirror. Mirror therapy can be switched on and used in all modules and games at the push of a button without much effort, which means immense time savings for the therapist.
Different modes for mirror therapy
There are three different modes for mirror therapy with CUREO. In the traditional mirror mode, the active, healthy hand is mirrored over the central axis. This means: If the patient raises the active hand (left in the example), in VR the avatar raises both the left and right hand. If the left hand moves upwards to the left, the right hand moves upwards to the right.
In the concurrent mirror mode, the non-active hand is always visualized about 30cm next to the active hand. There is no mirroring in the classical sense. Nevertheless, the second hand is visually taken along. This enables the effect of a mirror therapy without the patient having to cognitively rethink in a demanding way and thus being able to complete other programs, such as "Meteor" with both hands. He can thus control both virtual hands with one active hand in this mode.
The inverted mirror mode can quickly become complex and cognitively demanding, since here both arms can be moved simultaneously and these movements are then mirrored and transferred to the opposite arm in the virtual representation. This means that the real, left arm controls the virtual, right arm in a mirrored movement and vice versa.
[1] http://cbc.ucsd.edu/pdf/Synsth_Phant_Lmb_P_Roy_Soc.pdf accessed: 08/26/2021
[2] http://www.spiegeltherapie.de/index.php/template accessed: 08/26/2021
[3] https://www.schmerzgesellschaft.de/patienteninformationen/ergaenzende-verfahren/spiegeltherapie accessed: 08/26/2021
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